Closed-loop three-level charged quantum battery

Quantum batteries are energy storage or extract devices in a quantum system. Here, we present a closed-loop quantum battery by utilizing a closed-loop three-state quantum system in which the population dynamics depends on the three control fields and associated phases. We investigate the charging process of the closed-loop three-level quantum battery. The charging performance is greatly improved due to existence of the third field in the system to form a closed-contour interaction. Through selecting an appropriate the third control field, the maximum average power can be increased, even far beyond the most ideal maximum power value of non-closed-loop three-level quantum battery (corresponding to the most powerful charging obtainable with minimum quantum speed limit time and the maximum charging energy). We study the effect of global driving-field phase on the charging process and find the maximum extractable work (`ergotropy') and charging power vary periodically under different control field, with a period of 2π. Possible experimental implementation in nitrogen-vacancy spin is discussed.